MBP & External Monitor

Pretty sure you can use whatever size you want...

 

My MacBook Pro is connected to a 24" and I was planning to get a 30" for a time.

 

I'm in love with my 23" ACD. Besides being very easy on the eyes, it takes up a bit less space than a typical 24" @ the same resolution, and at the same time having a higher DPI which makes dual monitor mode with my MBP a bit more workable (ie. I can move a window between displays and it doesn't alter in size _too_ much). The resolution is pretty much the bare minimum I can get away with for a long day at work as a software dev. I have a similar setup at the office with a 24" dell and a 19" side display.

 

What do you mean with heat?

I believe the mbp can support the 30" ACD.

 

If you are just planning on using it for webbrowsing, desktop, and other 2d acceleration tasks or minimal 3d acceleration, it may increase it by a few degrees but likely won't make much of a difference.

However, if you currently play games at 1440x900 and make the jump in resolution to 1920x1200 it will likely get hotter working harder to push those extra 3d pixels in a high resolution 3d game

Simply stated - Desktop usage will be little or no temp increase, games will likely increase temp if at full resolution.